The prior art in manifolds for replacing relief valves in LPG storage applications characteristically has valve clusters mounted in one body whereby valves connect to a number of ports in the body which are circularly arranged and equally spaced about a common center. Each port is selectively closed one at a time by a single lever-mounted clapper disc which is indexed to rotate about said center and register with successive ports for said valves in said cluster. A cam mechanism operates the lever to clap the disc on each port connecting to a valve to be replaced as it is rotated by a miter gearset centrally mounted in the body of the manifold with a handwheel which is operationally connected thereto. See U.S. Pat. No. 2,720,214.
There is an established need for a manifold having two basic objectives: (1) to replace a plurality of relief valves individually mounted on tanks which cannot be removed for reasons of malfunction, periodic bench inspection, etc., without bleeding down the tank pressure and contents; and (2) as related to the background above.